Apparatus and method for transporting fluid-entrainable particles

ABSTRACT

Particles entrained in fluid are rapidly propelled through an elongated nozzle to an outlet where they contact a fluid barrier in the form of an air curtain which intersects the path of flow of the particles. Contact of the particles with the barrier subjects the particles to violent shock which, depending on the nature of particles being transported, will tend to break up or rupture the particles into constituent components. The air curtain, due to a &#39;&#39;&#39;&#39;Coanda effect,&#39;&#39;&#39;&#39; attaches itself to a flowattachment surface spaced from the curtain generator to move any particles entrained with the curtain in a second flow path along this surface. Other particles having sufficient inertia will penetrate the curtain so that particles are separated or classified, depending on the inertia they develop in the nozzle. If the particles are wet, and the entraining fluid is air, a drying of the particles also takes place.

United States Patent 1191 Reba et al. Jan. 7, 1975 APPARATUS AND METHODFOR 2.720.425 10/1955 Coanda .5302/63 TRANSPORTING FLUIDENTRAINABLE3,047,208 7/l962 Coanda 239/l)l(l. 7 3,315,806 4/1967 Sigwart 1 209/l43PARTICLES 3,575,353 4/l97l Sullivan 239/543 [751 lnvemors gm' g fiiz gfgg g FOREIGN PATENTS OR APPLICATIONS wash. 1,242,444 8/1960 France209/145 [73] Assignee: Crown Zellerback Corporation, San PrimaryE,mminer--Rbert Halper FI'aHCISCO, Callf- Attorney, Agent, or FirmThomasR. Lampe; Corwin 221 Filed: Apr. 17, 1974 Horton [21] App]. No; 461,560[57] ABSTRACT Related Application Data Particles entrained in fluid arerapidly propelled [63] Continuation of Ser- No 222 085 Jim 31 1972through an elongated nozzle to an outlet where they abandoned contact afluid barrier in the form of an air curtain which intersects the path offlow of the particles. 1521 vs. c1 209/3, 209/143, 209/145, cehteet ofthe PettieleS with the barrier Suhieete the 55/17, 239/116 7, 302/63particles to violent shock which, depending on the na- [51] Int. Cl B07b7/02 lure of particles being transported will tend to [58] Field OfSearch 175/422, 54; 166/174; "P or rupture the PertieleS httoeehstitueht P 239/41 DIG. 7 543 545; 302/ 3; 210/ 5; nents. Th6 aircurtain, clue IO a COflndtt effect," at- 209/145, 143, 31 132 155, 156 31; 244/42 taches itself to a flow-attachment surface spaced from CD thecurtain generator to move any particles entrained with the curtain in asecond flow path along this sur- {561 References Cited face. Otherparticles having sufficient inertia will pen- UNITED STATES PATENTSetrate the curtain so that particles are separated or classified,depending on the inertia they develop in the 3 3 5 gis Q nozzle. If theparticles are wet, and the entraining fluid 2255227 x 2 52 209x X isair, a drying of the particles also takes place. 2,460,884 2/1949 Kjost239/543 X 21 Claims, 6 Drawing Figures 1 k il 4 98 l l T 5m 90 96 lo 226 r 29 I2 43 l {9 M i 14 4. flit v 1. 0 54 0/ l l6 l ll L l 'L II"T f 1PATENTED JAN 7 5 SHEET 10F 2 APPARATUS AND METHOD FOR TRANSPORTINGFLUID-ENTRAINABLE PARTICLES This is a continuation of application Ser.No. 222,085, filed Jan. 31, 1972, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to a methodand apparatus for rapid transportation of fluid-entrainable particles.

A phenomenon known as the Coanda effect has been known for many years,as exemplified by US. Pat. No. 2,052,869 Coanda. Briefly, thisphenomenon can be described as the tendency of a fluid, which emergesfrom a slit under pressure, to attach itself or cling to and follow asurface in the form of an extended lip of the slit, which lip recedesfrom flow axis of the fluid as it emerges from the slit. This creates azone of reduced pressure in the area of the slit and so air or any otherentrainable material which is in the zone will become entrained and flowwith the fluid which has attached itself to the extended lip. A Coandanozzle may, therefore, be defined as a device which utilizes thisphenomenon.

Different uses have been suggested for Coanda nozzles; and, for example,one such use has been in the transportation of liquid or solid particlesas disclosed in US. Pat. No. 2,720,425 wherein internal nozzles areused.

It is also known(see, for example, an article by Dr. G. K. Korbacher,appearing in the January 1962 issue of Canadian Aeronautics and SpaceJournal, entitled The Coanda Effect at Deflection Surfaces Detached fromthe Jet Nozzle") that a fluid emerging from a slit under pressure willattach itself to and follow a receding deflection surface even thoughthe surface is spaced from the slit, and such flow attachment alsocauses a zone of reduced pressure and subsequent entrainment of air orother material in the zone of the attached flow.

Even though Coanda nozzles have been effectively used to rapidlytransport particulate material, as suggested by U.S. Pat. No. 2,720,425Coanda, it is often desirable, especially if the material is somewhatagglomerated, to subject the material to a greater rupturing ordisseminating force than is achieved by mere rapid in-line movement ofentrained material, and it would be desirable to accomplish this duringtransportation rather than require a separate operation to do so.Materials having different characteristics (eg., different specificweights) are often transported in mixed form,

and it would be desirable to provide at least some degree of separationor classification of the material during transportation thereof. Othertimes, it is desirable to provide good mixing of the material beingtransported during transportation thereof.

SUMMARY In accordance with one aspect of the present invention,fluid-entrainable particles are entrained in a moving fluid and advancedwith the fluid along a first flow path. A rapidly moving fluid curtainis provided which intersects this first flow path, and a flow-attachmentsurface is spaced from the fluid-curtain generator for the curtain toattach itself to and follow. The fluid curtain acts in a manner tosubject the particles to shock due to rapid deceleration of theparticles; and, if the particles have not developed sufficient inertiato penetrate the curtain, they will be reaccelerated and en trained forflow with the fluid curtain. While such shock may be sufficient todesirably break up'agglomerated particles, it also provides a zone ofintimate mixing for particles which follow the fluid curtain. If thereare other entrained particles that have developed sufficient inertia topenetrate the fluid curtain, such penetration will take place toseparate the material which penetrates from the material which isentrained with the fluid curtain.

Other aspects of the invention reside in the particular means forentraining the particles, and yet other aspects reside in takingadvantage of the Coanda effect to provide the flow-attachment of a fluidcurtain to a surface to which the fluid curtain becomes attached andfollows.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the present inventionis illustrated in the accompanying drawings in which:

FIG. I is a side elevational view of the apparatus of this invention,with parts broken away for clarity;

FIG. 2 is an enlarged side view of one of the nozzle assemblies of FIG.I, with parts broken away for clary;

FIG. 3 is an enlarged side view of another of the nozzle assemblies ofFIG. 1, with parts broken away for clarity;

FIG. 4 is a sectional view taken on the line 44 of FIG. 2;

FIG. 5 is a reduced sectional view taken on the line 55 of FIG. 1, withparts removed for clarity; and

FIG. 6 is a sectional view taken on the line 66 of FIG. 1.

GENERAL DESCRIPTION Referring to FIG. 1, particulate material to betransportedis supplied from a hopper 10 to a first flow path 11 for thematerial, which flow path is defined by the internal surfaces of a firstnozzle assembly 12. This material is entrained and rapidly transportedin a suitable fluid, such as air, in the direction of the arrow leadingfrom inlet end 13 to outlet end 14 of the first flow path 1 l.

A fluid-curtain generator in the form of a second nozzle assembly 15 ispositionedadjacent the outlet end of the first flow path so as togenerate a high velocity fluid curtain, such as high velocity air, whichemanates from a fluid-exit slit 16 in the second nozzle assembly, toprovide a fluid-curtain barrier which intersects the first material flowpath 11 at the outlet end thereof. The

fluid curtain is directed from the slit 16 to a flowattachment surface17, which at one end is in the form of a convexly curved, external endof nozzle 12 and the convexly curved end is spaced in close enoughproximity to the slit 16 for the fluid curtain to attach itself to andfollow surface 17 due to the aforementioned Coanda effect. In preferredform, the fluid curtain moves in a direction intersecting the first flowpath at an angle substantially perpendicular thereto. The fluid curtaincarries any entrained particles with it as it follows along externalnozzle surface 18 in the direction of the arrows. This fluid curtainentrains additional air from an external source (such as the atmosphere)which enters from around the end 19 of shroud 20 to further reduce theparticle concentration by entrainment of additional air. The internalsurface of shroud 20together with the external surface '18 of the firstnozzle assembly define a second flow path 21 having an inlet end incommunication with the outlet end of the first flow path 11. Theflow-attachment surface is so positioned as to preferably change thedirection of flow of any particles entrained by the curtain at least 90with respect to the direction the particles were traveling in the firstflow path.

In the preferred embodiment illustrated in the drawings, any particleswhich have been entrained by the fluid curtain then move along thesecond flow path in the direction of the arrows, and the direction ofmovement of the particles in the second flow path 21 is opposite or 180to the direction the particles have moved along the first flow path 11.

The entrained particles are moved from the second flow path into anysuitable collector 22. While the type of collector is not critical, ithas been illustrated as a receptacle having a screen 23 to permit air topass out of the receptacle while retaining the particles therein.

At the outlet end prior to encountering the fluid curtain in the firstflow path 1 l, the particles are at a rather high velocity, preferablyat least 40 feet per second when the entraining fluid is gaseous, suchas air. The fluid curtain emanating from slit 16 which intersects thisflow path also is moving at a high velocity which is preferably at least300 feet per second when a gaseous fluid, such as air, is used toprovide the curtain. The particles upon contact with the fluid curtainthereby undergo a rather violent shock so as to cause a rupture orbreaking up of any agglomerated particles. If the particles have notachieved sufficient inertia to penetrate the fluid curtain, they will beentrained in the fluid curtain and move along the second flow path 21.There may, however, be particles which have achieved sufficient inertiain the first flow path 11 to penetrate the fluid curtain. Theseparticles, after penetrating the curtain, are moved by suitable meansfor conveying them in a direction away from the second flow path of theentrained particles.

Actually, the particles which penetrate the curtain may be classifiedfurther into two general types, namely, those which have developedsufficient inertia to penetrate the fluid curtain without substantialdeflection of the particles, and those which are partially deflected bythe air curtain, but which, due to centrifugal force, do not follow theair curtain but are expelled therefrom in a direction extendingsubstantially 90 from the direction of flow in the second flow path 21.This further classification is optional and, if desired, all of thematerial which penetrates and is not moved along the second flow path 21could be collected into a single fraction.

To summarize, the present invention in a preferred embodiment not onlyhas capability of exerting forces by contact of particles with the fluidcurtain which causesdeagglomeration and intense mixing in the zone ofthe curtain, but the invention also has capability of classifyingparticles into threegeneral fractions, depending on the inertia achievedby the particles at the outlet end 14 of the first flow path. A firstfraction are the particles which do not develop sufficient inertia topenetrate the curtain or have lost inertia due to deagglomeration, andthe particles in the first fraction are entrained by the fluid curtainand moved along the second flow path 21. A second fraction are thoseparticles developing sufficient inertia to penetrate the curtain withoutbeing substantially deflected, and the particles in the second fractionenter the zone between suitable conveying means in the form of anotherCoanda flowattachment surface 24 anda shroud 25 where they are moved toany suitable collector. Fluid for entraining this second fraction issupplied from slit 26 which is located on the opposite side of the fluidcurtain supplied by slit 16 from the first nozzle assembly 12. A thirdfraction are those particles developing an inertia between thatdeveloped by the first and second fractions. This third fraction isexpelled from the air curtain into a suitable collector 27.

In order to obtain an understanding of the structural detail of apreferred embodiment for a first nozzle assembly 12 supported withingenerally cylindrical shroud 20, reference should be made to FIGS. 3 and6, viewed in connection with FIG. 1. The shroud 20 is supported from anysuitable supporting base 28 through the medium of a clamp member 29.

The first nozzle assembly 12 has a main body portion in the form of anelongated diffuser member 30 which is supported concentrically withinand spaced from the inner surface of shroud 20. The diffuser member isannular in cross-sectional configuration in that it has a generallycylindrical outer surface 18, and an inner surface 31 which divergesfrom a throat portion 32 to outlet end 14. The external surface of thediffuser is provided with an externally-threaded,.recessed portion atthe throat end 32 to receive a first fluid-exit slitforrning member 33.The member 33 is annular in cross-sectional configuration and one endthereof is provided with internal threads 34 for receiving the threadedend of the diffuser member. As seen at FIG. 3, the inner surface 35 ofmember 33 is convexly curved and the end 36 opposite the threaded end isutilized to define one side of fluid-exit slit 37. This slit 37 islocated adjacent the inlet end 13 of the first flow path for thematerial. The inner surface 35 of member 33, together with the materialinlet end of diffuser 30, defines a throat portion 32 for the firstmaterial flow path in that the surface 35 converges from the slit 37toward the throat. The opposite side of fluid-exit slit 37 is defined byan inwardly projecting flange 38 on an annular, external slit-definingmember 39. A recessed external surface 40 on member 33, together withinternal surface 41 on member 39, defines a fluid-pressure chamber 42which is in communication with slit 37, and the chamber receives fluid,such as air, under pressure from a suitable fluid-supply line 43. Thefluid under pressure therefore emerges from the slit and, due to theCoanda effect, attaches itself to and follows surface 35 in a convergingpath to the throat 32. From the throat, the flow path diverges to theoutlet end 14 of the nozzle assembly 12. This rapidly moving airestablishes a zone of reduced pressure on the opposite side of slit 37from surface 35 so that the rapidly moving air entrains additional airand any particulate material located in this zone of reduced pressure.Particles entrained by this fluid are thereby rapidly transported frominlet end 13 to outlet end 14 of the first flow path defined by internalsurfaces of the first nozzle assembly.

It is desirable to provide means for adjusting the size of slit 37; and,to accomplish this, there is a threaded connection at 44 between themembers 33 and 39. Therefore, if member 39 is turned in one direction,the slit size is increased, and if it is turned in the other direction,the slit size is decreased. In order to permit an operator to ascertainthe extent of increase or decrease of the slit size without actualmeasurement, a springbiased detent 45 extends slightly from the recessedsurface of diffuser member 30. Cooperating with the detent 45 is aplurality of countersunk portions 46 formed in and equidistantly spacedaround the end of member 39. If, for example, there are 36 countersunkportions, the operator will know that the member 39 has to be turned tomove the detent from one countersunk portion into the one next adjacent.Because of the threaded connection of member 33 to member 39, theoperator can readily ascertain that each turn of 10, depending on thedirection, will increase or decrease the size of slit 37 a predeterminedamount, depending on the thread pitch in the threaded connection. Asealing ring 47 is wedged between the outer surface of member 33 and theinner surface of member 39.

To further complete the outlet end 14 of the nozzle assembly 12, anannular member 48 is affixed thereto through the medium of fasteners 49.The member 48 has a convexly-curved, external surface to provide theaforementioned flow-attachment surface 17 for the fluid curtain whichexits from slit 16 in the second nozzle assembly 15.

A conical member 51 is secured to member 39 by appropriate fasteners 52,and the external converging surface of this conical member, therefore,acts as a diffuser in the sense that the cross-sectional area of thesecond flow path 21 is gradually increased as the particles move in adirection toward the point 53 of the conical member. A material supplyduct 54 leads to an internal cavity 55 in the conical member, and thiscavity is in direct communication with the first flow path 11 leadingfrom slit 37, to continually supply material to be transported to thezone adjacent the slit for entrainment of such material by fluid exitingfrom the slit because of the aforementioned Coanda effect.

Structural details of a preferred embodiment of a second nozzle assemblyare illustrated at FIG. 2. A generally cylindrical outer fluid conduitmember 56 has a fluid supply duct 57 in communication therewith, and anexterior collar 58 having a sloping exterior surface 59 extendsconcentrically around and is secured to the outer surface of the conduit56. An inner, generally cylindrical, fluid conduit member 60 issupported concentrically within and spaced from the outer member 56, andthis inner conduit is in communication with supply duct 61. An extension62 for conduit 60 is utilized to convey fluid under pressure fromconduit 60 to fluid-exit slit 16 via openings 63 which lead to a cavity64 in communication with this slit. The extension member 62 is connectedto conduit 60 through the medium of an annular connector member 65.External, re-

cessed, surface portions 66 of the connector member 65 are threaded toreceive the internal threads of annular, fluid-exit slit-forming member67 which has a convex outer surface portion 68 leading away from slit 26to form one boundary for this slit. The member 67 has countersunkportions 70 formed therein at one end thereof for receiving aspring-biased detent 71 in extension member 65 to permit adjustabilityof the size of slit 26 in the same manner as was explained in connectionwith adjusting the slit size in first nozzle member 12. A sealing ring72 is wedged between the outer surface of connector member 65 and theinner surface of member 67.

Spacer rings 73 are positioned around extension member 62 to wedge aring-like fluid-exit slit-forming member 74 into place between acircumferential external flange 75 on the extension member 62 and acircumferential external flange 76 on connector member 65.

Surface 77 on flange 75 defines one boundary of fluid-exit slit 16. Theother boundary of slit 16 is defined by an extension lip 78 on a collar79, which collar is threaded onto external threads 80 on extensionmember 62 so that the size of slit 16 can be adjusted by turning collar79 in relation to member 62. The flange 75 and collar 79 havecomplementary, generally cylindrical, external surfaces and are of sucha size so that the slit 16 can be placed concentrically within the sameplane as-the plane defined by the extreme left end (as viewed in FIG. 1)of flow-attachment surface 17.

Means for permitting the operator to determine the extent of increase ordecrease in the size of slit 16 is provided by a spring-biased detent 81in surface 82 of collar 79, which detent is adjustably received incountersunk portions 83 in ring-like member 84, the latter number alsobeing threaded onto the extension member 62. A sealing ring 85 is wedgedbetween the outer surface of member 62 and the inner surface of member79. A nose cone 86 is threaded onto the extreme right end (as viewed atFIG. 2) of extension member 62. As seen at FIG. 1, the nose coneprojects from slit 16 concentrically into the end of the first nozzle12, and the cone 86 serves as a guiding surface causing particles in thefirst flow path to be moving at substantially right angles to the fluidcurtain when contact is made with the curtain.

Fluid under pressure reaches chamber 87 supplying fluid to the slit 26via openings 88 through connector member 65. Fluid exiting from slit 26attachesitself to surface 68 and follows this surface due to theaforementioned Coanda effect. This attached fluid entrains additionalair and any particles which are in the vicinity of the slit. Externallyspaced, cylindrical shroud 25, together with surface 24, defines a flowpath for material moving along surface 24 in the direction of the arrows(FIG. 1).

As indicated above, collector 27 is utilized to collect thosetransported particles which have not developed sufficient inertia at theoutlet of the first nozzle 12 to continue in a straight path so that theparticles are deflected by the air curtain and expelled into thiscollector. As illustrated at FIGS. 1 and 5, the collector 27 has acurved, inner circumferential surface 89 which cooperates with back wall89a so as to only partially enclose the space between shrouds 20 and 25,leaving a space 90 for additional air to be entrained from theatmosphere. Such entrainment of additional air is caused due to flowattachment on surfaces 17 and 24 by air exiting from slits l6 and 26.Optionally, an enclosed chamber could enclose space 90 with air beingsupplied under pressure to the chamber. An internal, curved divider 91in the collector defines an inlet 92 for receiving air to be entrainedthrough this inlet or received under pressure, and an outlet 93 forremoving air and any material entrained thereby. The air from inlet 92follows a tangential swirling flow path around the inner surface of thecollector and leaves through outlet 93 carrying entrained material withit. Centrifugal forces throw the particulate material against surface 89and the flow causes the material to follow this surface to outlet 93.Instead of using a positive pressure air to supply inlet 92, it ispossible to utilize a Coanda nozzle (not shown) in outlet 93 whichdirects air and entrained material outwardly for removal from thecollector.

An L-shaped supporting frame member 94, which is generally rectangularin cross-section, is secured to the clamp 29 to adjustably support thesecond nozzle assembly 15 therefrom. The supporting arrangement is suchthat the first and second nozzle assemblies are adjustably supportedrelative to each other to permit adjustment of the position of thefluid-exit slit 16 relative to external flow-attachment surface 17 ofthe first nozzle assembly. A complementary L-shaped supporting framemember 95 extends through shroud 25 and is secured at one end to thesecond nozzle assembly 15. The other end of the frame 95 has a noseportion 96 having a threaded aperture 97 extending therethrough and, asis clear from FIG. 1, the end of frame 95 is snugly positioned withinone leg of frame 94. A crank arm 98 is rotatably supported on frame 94,and the crank is used to turn a threaded shaft 99 which is received inthreaded aperture 97. Thus, rotation of crank arm 98 will imparthorizontal movement to second nozzle assembly 15 with respect to firstnozzle assembly 12 and so this provides means for adjusting the positionof exit slit 16 on the second nozzle assembly 15 relative to theflow-attachment surface 17 on the first nozzle assembly Reference shouldbe made to FIG. 1 for illustration of proper relative positioning of thecomponent parts of the apparatus of this invention. The slit 16 shouldbe in approximately the same place as a plane into which all points onthe extreme left tip (as viewed at FIG. 1) of the attachment surface 17would fall. It is possible, however, to obtain flow attachment of thefluid curtain from slit 16 onto surface 17 by moving the slit as much asone-half inch to the left of the plane. It is usually not desirable tomove the slit to the right of the plane because, while it is stillpossible to get some flow attachment of the fluid curtain onto surface17, positioning of the slit to the right of this plane generates backpressure and instability of flow in the first nozzle assembly 12.

As has been indicated above, means are provided for adjusting the widthof slits 16, 37 and 26. It is desirable that this range of adjustabilitypermits the slit width to be adjusted between a range of 0.001 inch to0.150 inch. For most uses presently contemplated, the slit width whichis chosen will lie between about 0.003 inch and 0.050 inch.

For a given slit width, an increase in the pressure of fluid that issupplied to the slit will increase the velocity of the fluid as it exitsfrom the slit and moves over its flow attachment surface; and,therefore, the velocity imparted to the material entrained in this fluidwill increase. Pressures that may be used in supplying transportingfluid to the slits may vary over a rather wide range, such as betweenabout 1 psig and 400 psig, depending on the velocity it is desired toachieve and the nature of the operation desired to be performed on thematerial being transported. For most uses presently contemplated, thepressures of the fluid supplied to the slits will lie between about psigand 100 psig.

It is important that the velocity of the-fluid with its entrained flowsupplied from slit 37 when it reaches the outlet end 14 of the firstflow path 11 not be so great as to cause detachment of the fluid curtainsupplied by slit 16 onto surface 17. Otherwise, none of the materialwould follow the second flow path 21. Therefore, in most instances, theoperator will select the pressure he desires for fluid exit from slit16, and initially cause fluid to exit from this slit and attach itselfto follow surface 17. The operator will then gradually raise thepressure of the fluid exiting from slit 37 until a value is reachedwhere the flow of the fluid curtain supplied from slit 16 detaches fromthe surface 17. This is the limiting pressure to slit 37. For the slitsizes chosen, the fluid supplied to slit 37 must then be at a pressureless than would cause flow detachment from surface 17. Conversely, anoperator could first predetermine a required material through-put rateachieved by adjusting pressure and slit size for slit 37. The operatormay then gradually raise the pressure and/or adjust slit size of exitslit 16 until a condition of flow attachment of the curtain from slit 16to surface 17 is obtained.

As indicated above, the flow velocities, as governed by pressures andslit sizes, chosen for the entraining fluid in flow path 11, as comparedto the flow velocity of the fluid curtain from slit 16, will depend onthe type of operation that it is desired to perform on the materialbeing transported. If, for example, the material being transportedincludes a mixture of two types of material (one type of which iscapable of developing higher inertia than the other), and if separationof the two types of material is desired, then it will be desirable toestablish as high a velocity as possible in flow path 11 without causingdetachment of the curtain from attachment surface 17.

On the other hand, if it is mostly desired to cause a breaking up,mixing'or deagglomeration of particles being transported, then thevelocity of the fluid curtain from slit 16 will be adjusted to be highin relation to the velocity of the particles transported in first flowpath 11. In the latter instance, it will be highly preferable to utilizea higher pressure for the fluid that supplies slit 16, as compared tothe pressure of the fluid that supplies slit 37.

While, as indicated above, velocities imparted to the tain from slit 16to achieve a velocity of at least 300 feet per second, these statedvelocities being for most types of particles and where a gaseousentraining fluid is used to transport the particles.

The specific type of material or particles to be transported, so long asthey are entrainable in a fluid, are not critical to the presentinvention.

Particles are any fluid-entrainable materials which maybe entrained inthe transporting fluid at the velocities employed. Thus, in certaininstances, it may be desirable to transport such particles as groundmetallic ores, metal particles, cereal grains, wood chips, cellulosefibers, fine powders, and many other materials by use of the method andapparatus of this invention.

Notwithstanding the fact that many additional types of particles may betransported, examples which are hereinafter presented illustrate the useof this invention with certain types of material, the treatment of whichhas been found to be especially advantageous. When reference is made inthese examples to polyethylene fibers. such fibers are of a type thatmay be formed, for example, in accordance with the teaching of U.S. Pat.

9 applications Ser. Nos. 27,053 now abandoned, filed Apr. 9, 1970; and69,194 now abandoned, filed Sept. 3, 1970. Such polyethylene fibers,after they have been suitably prepared for making synthetic paper, areof papermaking size, i.e., about 0.2 to 3 millimeters in length and havea diameter or width of about to 400 microns. When reference is made torayon staple fibers,

dividual weights of the fibers, water and sand in the input mixture and,also, in each of the collected fractions were determined. Measurementswere made of the particle size of the sand in the input mixture and ineach fraction. The specific weight of the fibers is about 0.95, and thespecific weight of the sand is about 2.56. The results are tabulated inthe following Table I.

such fibers are those supplied by American Viscose Division of FMCCorporation and are inch in length and 3 denier. The rayon staple, assupplied, is in the form of many individual fibers closely packedtogether to form fiber bundles.

With further reference to the examples which follow, when reference ismade to the F fraction, it means that fraction of material which hasbeen entrained by the fluid curtain and has been collected by thecollector 22. The R fraction is a fraction which has penetrated thecurtain and is collected downstream of the surface 24. The C fraction isa fraction which has been collected in collector 27.

In the examples which follow, the apparatus which was used had thefollowing physical and operating characteristics (unless otherwisenoted):

Size Pressure (inches) (ps g) Pressure supplied by line 43 30 Width ofslit 37 0.006 Length of nozzle from slit 12 to end 14 20.0

Diameter of throat 32 0,6 45 Internal diameter of diffuser at outlet end14 1.53

Diameter of external surface 18 300 Internal diameter of shroud 20 5.50Pressure supplied to slit 16 30 Width of sin 16 .020 External diameterof slit 16 .750 Horizontal distance (to the left as viewed at FIG. 1) ofslit 16 to the vertical plane of the ex treme left end of surface 17 .06

Pressure supplied to slit 26 30 Width of slit 26 .003 External diameterof surface 24 (largest) 1.8

Internal diameter of shroud 25 4.0 Horizontal separation distance ofends of shrouds 20 and 25 1.5

Internal diameter of collector 27 14.0 Internal diameter of flange 891110.0

EXAMPLE 1 In this example, wet synthetic polyethylene fibers wereintimately mixed with sand and the mixture was transported through theapparatus described above. 1n-

The foregoing data clearly indicates that most of the fibers, which havesubstantially less specific weight than the sand, are entrained by thefluid curtain and pass to the F fraction. The sand develops sufficientinertia to permit it to penetrate the fluid curtain, as is demonstratedby the fact that, of the total sand transported, less than 2 percent wascarried with the fibers to the F fraction. Much less sand is containedin the C fraction than in the R fraction. The data further indicatesthat there is a tendency for the coarser sand to go into the R fractionand the finer sand to be deflected and captured in the C fraction.Moisture was removed from the fibers which passed to the F fraction, asevidenced by the fact that the input fibers were only 74 percent O.D.(oven dry), but the fibers in the P fraction were 93 percent O.D. (ovendry).

EXAMPLE 2 In this example, polyethylene fibers were utilized in amixture which also had some small polymer chunks therein, the chunksbeing heavier than the individual fibers. included, also, in the mixturewere some severely entangled fibers. A sample from this mixture (priorto being transported through the apparatus described above) was used tomake a 6.25-inch diameter, 36 pound/ream basis weight, handsheet in aconventional manner by dispersing the mixture in water in a vessel,shaking the vessel one hundred times, and then using the dispersedmixture to form the handsheet on a forming wire in a conventionalhandsheet mold. The handsheet was calendered at pounds per lineal inch.The presence of polymer chunks and agglomerated fiber bundles in thehandsheet is indicated by the extent and size of transparent spots thatappear in the handsheet after such calendering, because such chunks andbundles have a tendency to transparentize. After passing another samplefrom the same mixture through the apparatus described above, handsheetswere also formed and calendered from the F, R and C fractions.Measurements were made of transparent spots formed in each handsheet byusing a template to measure the size and by counting the number. Theresults are tabulated in the following Table II.

TABLE ll Size and Number of Transparent Spots Over Less than 8mm 8mm 4mm2mm 2mm input 45 61 96 *100 *300 R Fraction 7 18 40 76 *200 C FractionI3 26 *133 *500 F FraCtlOn 0 0 70 The numbers of [00 or over areapproximations.

The above data indicates there is an overall breaking up of fiberbundles, as evidenced by the reduction in large spots in all of thetreated fractions, as compared to the input fraction. The data alsoindicates there is a tendency for the R fraction to obtain the largerchunks and bundles, and a tendency for the C fraction to obtain thesmaller chunks and bundles because the smaller chunks and bundles havemore of a tendency to be deflected by the fluid curtain.

EXAMPLE 3 In this example, wet polyethylene fibers which were 57 percentO.D. (oven dry) with a moisture content of 43 percent were passedthrough the apparatus as described above, except that the pressure offluid supplied to fluid-exit slits 16 and 37 were varied. The pressure Pis the air pressure supplied to slit 37, and the pressure P is the airpressure supplied-to slit 16. The pressure supplied to slit 26 is thesame as that supplied to slit 16. Measurements were made of thepercentage of the original fibers supplied which were collected at eachof the fractions for each pressure combination, and measurements weremade of the moisture content on an OD. (oven dry) basis for the Ffraction. The results are tabulated in the following Table lll.

The above data indicates that as the pressure from slit 37 increases,compared to the pressure from slit 16, the velocity imparted to thefibers also increases in the first flow path, and so more fiberspenetrate the fluid curtain. Data also indicates that some drying of thefibers takes place. The amount in the F fraction could be increased bymoving the shroud 20 to the left (as viewed at FIG. 1) to intercept someof the particles that otherwise would pass to the C fraction. lfpressures are held constant, an increase in the size of slit 37willdecrease the amount of material in the F fraction. An increase in thesize of slit 16 will increase the amount of material in the F fraction.An increase in the amount of material in the R fraction can beaccomplished by increasing pressure and/or slit size of slit 26.

EXAMPLE 4 In this example, ll6 grams of rayon staple fibers (in the formof fiber bundles, as supplied from the vendor indicated above) wereplaced in a graduated beaker and, without external compression, werefound to occupy a volume of 0.8 liter. These fiber bundles were passedthrough the apparatus indicated above, except the pressure of airsupplied to slits l6 and 37 was 40 psig. Sixty-seven grams of the fiberswere collected as an F fraction, and 49 grams total was collected at theR and C fractions. The fibers collected at the F fraction were placed ina graduated beaker without external compression and found to occupy avolume of 6.0 liters; and, upon viewing, had the appearance of a mass ofseparated fibers. This indicates that the inventive treatment waseffective to break up and fluff the original fiber bundles. The R and Cfractions, when placed in a beaker, occupied a volume of 1.5 liters witha visual appearance ofa mixture of fiber bundles and separated fibers. 1

EXAMPLE 5 In this example, a sample including substantially equalquantities of dry polyethylene fibers and rayon staple fibers wereplaced in a vessel and it was attempted to mix the fibers together byhand-shaking but only a very poor mixture was obtained. This sample wasthen transported through the apparatus of the present invention and asample obtained at the F fraction showed the polyethylene fibers and therayon staple fibers to be intimately mixed with each other. Thissuggests that the forces encountered by the particles when they contactthe fluid curtain are effective to intermix different types of fiberswhich are of such a nature as to be both transported by the fluidcurtain. Rather than using different types of fiber, it is possible touse the method and apparatus of this invention to incorporate fine,lightweight powders into uniform admixture with fibers when both aresimultaneously transported through the apparatus. It is alsocontemplated that vapors or very fine particles functioning as coatingagents for the entrained material could be added to the entraining fluidto take advantage of the mixing zone provided by the fluid curtain tocoat the transported particles.

From the above, it should be clear that the method and apparatus of thepresent invention has utility for achieving a number of desired resultsin transporting particulate material, depending on the nature ofmaterial being transported and the operating conditions chosen.Separation of particles capable of developing different inertias may beobtained. It is also possible to achieve good mixing and deagglomeratingof particulate matter due to forces acting on the particles when theycontact the fluid curtain. Drying of wet fibrous material has also beendemonstrated.

While the foregoing specification has set forth specific embodiments anddesirable uses of the invention in detail for purpose of making acomplete disclosure, various other embodiments and uses will occur tothose skilled in the art, but will fall within the spirit and scope ofthe invention defined in the following claims.

We claim:

1. Apparatus for transporting and treating fluidentrainable particlescomprising:

a. means defining a first flow path having inlet and outlet ends;

b. means for advancing the particles with an entraining fluid along thefirst flow path from the inlet to the outlet end thereof;

c. a fluid-curtain generator having a fluid-exit slit adjacent saidoutlet of said first flow path and additionally having means forprovidingfluid under pressure to said generator fluid-exit slit to forma high velocity fluid-curtain barrier intersecting said first flow path;and,

d. a substantially curved flow-attachment surface spaced from saidfluid-curtain generator fluid-exit slit across said first flow path andpositioned in close enough proximity to said high velocity fluidcurtainfor said high velocity fluid curtain, and any particles entrainedthereby, to attach to said flowattachment surface and to follow saidflowattachment surface due to the Coanda effect in a second flow path,whereby any particles entrained by said high velocity fluid-curtain willbe separated from any other particles exiting from the first flow pathoutlet that have suff ciently higher inertial characteristics to permittheir passage through said high velocity fluid curtain.

2. The apparatus as set forth in claim 1 wherein said first flow path isdefined by internal surfaces of a first nozzle assembly, and said meansfor advancing the particles comprises means defining a first nozzleassembly fluid-exit slit located adjacent the inlet end of said firstflow path to direct entraining fluid through said first nozzle assemblyfluid-exit slit and along said internal surfaces in a direction fromsaid inlet end to said outlet end.

3. The apparatus as set forth in claim 2 wherein said internal surfacesconverge from said first nozzle assembly fluid-exit slit to a throatportion and diverge from said throat portion to said outlet end.

4. The apparatus as set forth in claim 2 wherein means for adjusting thefirst nozzle assembly fluid-exit slit size is provided.

5. The apparatus as set forth in claim 1 wherein said first flow path isdefined by internal surfaces of a first nozzle assembly, and saidflow-attachment surface comprises an external end of said first nozzleassembly.

6. The apparatus as set forth in claim 5 which further includes a shroudspaced outwardly from the external surface of the first nozzle assembly,said shroud and external surface together defining said second flow pathhaving an inlet end in communication with the outlet end of said firstflow path.

7. The apparatus as set forth in claim 6 wherein the direction of flowin said second flow path extends opposite to the direction of flow insaid first flow path.

8. The apparatus as set forth in claim 1 wherein means for adjustingsaid fluid-curtain generator fluidexit slit size is provided.

9. The apparatus as set forth in claim 1 wherein said second flow pathis in communication with an external fluid source for providingadditional fluid to further reduce particle-fluid concentration byentrainment of the additional fluid.

10. Apparatus for transporting and treating fluid entrainable particlescomprising:

a. a first nozzle assembly provided with internal and externalparticle-flow-directing surfaces, said internal surface having aparticle inlet end and a particle outlet end and means for moving theparticles in an entraining fluid in a first flow path from the inlet tothe outlet end; a second nozzle assembly including means defining afluid-exit slit positioned adjacent the outlet end of the first nozzleassembly, and means for directing the fluid through the slit to providea fluid curtain moving in a direction intersecting the first flow path;

c. said external particle-flow-directing surface of said first nozzlecomprising a substantially curved external flow-attachment surfacespaced from said fluidcurtain means and in close enough proximitythereto for said fluid curtain, and any particles entrained thereby, tofollow said flow-attachment surface in a second flow path.

11. The apparatus as set forth in claim 10 wherein the particle outletend of said first nozzle assembly is annular in cross-sectionalconfiguration, and external surfaces of the means defining thefluid-exit slit are generally cylindrical, and the slit is positioned insubstantially the same place as that defined by the annular,particleoutlet end of the first nozzle assembly.

12. The apparatus as set forth in claim 10 wherein the first and secondnozzle assemblies are adjustably supported relative to each other bymeans that permit adjustment of the position of the fluid-exit slit ofthe second nozzle assembly relative to the external flowattachmentsurface of the first nozzle assembly.

13. The apparatus as set forth in claim 10 wherein a shroud is supportedin spaced relationship from the external particle-flow-directing surfaceof the first nozzle assembly to define a boundary for said second flowpath for any particles entrained by said fluid curtain to follow saidflow-attachment surface.

14. The apparatus as set forth in claim 10 which further includes meansfor conveying any particles which penetrate the fluid curtain in adirection away from the second flow path.

15. The apparatus as set forth in claim 14 wherein said conveying meansincludes means defining a second fluid-exit slit located on the oppositeside of said fluid curtain from said first nozzle assembly for directingfluid in flow-attached relationship onto a second substantially curvedexternal flow-attachment surface.

16. The apparatus as set forth in claim 10 wherein said conveying meansincludes a collector device.

17. The apparatus as set forth in claim 16 wherein said collector deviceincludes a curved, internal surface in communication with a conveyingfluid inlet and a particle outlet for supplying conveying fluid intangential flow to the internal surface in a direction leading from theinlet to the outlet and removing particles from the outlet with theconveying fluid.

18. The apparatus as set forth in claim 14 wherein 7 said conveyingmeans includes first conveying means for conveying any particles havingsufficient inertia supplied in said first nozzle to penetrate the fluidcurtain without substantial deflection of the particles by said fluidcurtain, and second conveying means for conveying particles having lessinertia supplied in said first nozzle than said particles removed bysaid first conveying means, but greater inertia than particles whichfollow said flow-attachment surface.

19. A method of transporting and treating fluidentrainable particlescomprising:

a. advancing the particles entrained in a fluid from an inlet to anoutlet end of a first flow path;

b. providing a high velocity fluid-curtain barrier which intersects thefirst flow path at the outlet end thereof by forcing a fluid through aslit communicating with said first flow path under pressure; and,

c. directing the pressurized high velocity fluid curtain onto asubstantially curved external flowattachment surface receding from thecurtain and spaced across the first flow path from said slit so movingsuch penetrating particles, and entraining for movement with the fluidcurtain particles which do not develop sufficient inertia to penetratethe fluid curtain.

21. The method as set forth in claim 20 which further includesseparating particles which penetrate the fluid curtain into a firstfraction which move along a path substantially coextensive with thefirst flow path, and a second fraction which partially turn with thefluid curtain and are then expelled therefrom.

1. Apparatus for transporting and treating fluid-entrainable particlescomprising: a. means defining a first flow path having inlet and outletends; b. means for advancing the particles with an entraining fluidalong the first flow path from the inlet to the outlet end thereof; c. afluid-curtain generator having a fluid-exit slit adjacent said outlet ofsaid first flow path and additionally having means for providing fluidunder pressure to said generator fluid-exit slit to form a high velocityfluid-curtain barrier intersecting said first flow path; and, d. asubstantially curved flow-attachment surface spaced from saidfluid-curtain generator fluid-exit slit across said first flow path andpositioned in close enough proximity to said high velocity fluid-curtainfor said high velocity fluid curtain, and any particles entrainedthereby, to attach to said flow-attachment surface and to follow saidflow-attachment surface due to the Coanda effect in a second flow path,whereby any particles entrained by said high velocity fluid-curtain willbe separated from any other particles exiting from the first flow pathoutlet that have sufficiently higher inertial characteristics to permittheir passage through said high velocity fluid curtain.
 2. The apparatusas set forth in claim 1 wherein said first flow path is defined byinternal surfaces of a first nozzle assembly, and said means foradvancing the particles comprises means defining a first nozzle assemblyfluid-exit slit located adjacent the inlet end of said first flow pathto direct entraining fluid through said first nozzle assembly fluid-exitslit and along said internal surfaces in a direction from said inlet endto said outlet end.
 3. The apparatus as set forth in claim 2 whereinsaid internal surfaces converge from said first nozzle assemblyfluid-exit slit to a throat portion and diverge from said throat portionto said outlet end.
 4. The apparatus as set forth in claim 2 whereinmeans for adjusting the first nozzle assembly fluid-exit slit size isprovided.
 5. The apparatus as set forth in claim 1 wherein said firstflow path is defined by internal surfaces of a first nozzle assembly,and said flow-attachment surface comprises an external end of said firstnozzle assembly.
 6. The apparatus as set forth in claim 5 which furtherincludes a shroud spaced outwardly from the external surface of thefirst nozzle assembly, said shroud and external surface togetherdefining said second flow path having an inlet end in communication withthe outlet end of said first flow path.
 7. The apparatus as set forth inclaim 6 wherein the direction of flow in said second flow path extendsopposite to the direction of flow in said first flow path.
 8. Theapparatus as set forth in claim 1 wherein means for adjusting saidfluid-curtain generator fluid-exit slit size is provided.
 9. Theapparatus as set forth in claim 1 wherein said second flow path is incommunication with an external fluid source for providing additionalfluid to further reduce particle-fluid concentration by entrainment ofthe additional fluid.
 10. Apparatus for transporting and treating fluidentrainable particles comprising: a. a first nozzle assembly providedwith internal and external particle-flow-directing surfaces, saidinternal surface having a particle inlet end and a particle outlet endand means for moving the particles in an entraining fluid in a firstflow path from the inlet to the outlet end; b. a second nozzle assemblyincluding means defining a fluid-exit slit positioned adjacent theoutlet end of the first nozzle assembly, and means for directing thefluid through the slit to provide a fluid curtain moving in a directionintersecting the first flow path; c. said externalparticle-flow-directing surface of said first nozzle comprising asubstantially curved external flow-attachment surface spaced from saidfluid-curtain means and in close enough proximity thereto for said fluidcurtain, and any particles entrained thereby, to follow saidflow-attachment surface in a second flow path.
 11. The apparatus as setforth in claim 10 wherein the particle outlet end of said first nozzleassembly is annular in cross-sectional configuration, and externalsurfaces of the means defining the fluid-exit slit are generallycylindrical, and the slit is positioned in substantially the same placeas that defined by the annular, particle-outlet end of the first nozzleassembly.
 12. The apparatus as set forth in claim 10 wherein the firstand second nozzle assemblies are adjustably supported relative to eachother by means that permit adjustment of the position of the fluid-exitslit of the second nozzle assembly relative to the externalflow-attachment surface of the first nozzle assembly.
 13. The apparatusas set forth in claim 10 wherein a shroud is supported in spacedrelationship from the external particle-flow-directing surface of thefirst nozzle assembly to define a boundary for said second flow path forany particles entrained by said fluid curtain to follow saidflow-attachment surface.
 14. The apparatus as set forth in claim 10which further includes means for conveying any particles which penetratethe fluid curtain in a direction away from the second flow path.
 15. Theapparatus as set forth in claim 14 wherein said conveying means includesmeans defining a second fluid-exit slit located on the opposite side ofsaid fluid curtain from said first nozzle assembly for directing fluidin flow-attached relationship onto a second substantially curvedexternal flow-attachment surface.
 16. The apparatus as set forth inclaim 10 wherein said conveying means includes a collector device. 17.The apparatus as set forth in claim 16 wherein said collector deviceincludes a curved, internal surface in communication with a conveyingfluid inlet and a particle outlet for supplying conveying fluid intangential flow to the internal surface in a direction leading from theinlet to the outlet and removing particles from the outlet with theconveying fluid.
 18. The apparatus as set forth in claim 14 wherein saidconveying means includes first conveying means for conveying anyparticles having sufficient inertia supplied in said first nozzle topenetrate the fluid curtain without substantial deflection of theparticles by said fluid curtain, and second conveying means forconveying particles having less inertia supplied in said first nozzlethan said particles removed by said first conveying means, but greaterinertia than particles which follow said flow-attachment surface.
 19. Amethod of transporting and treating fluid-entrainable particlescomprising: a. advancing the particles entrained in a fluid from aninlet to an outlet end of a first flow path; b. providing a highvelocity fluid-curtain barrier which intersects the first flow path atthe outlet end thereof by forcing a fluid through a slit communicatingwith said first flow path under pressure; and, c. directing thepressurized high velocity fluid curtain onto a substantially curvedexternal flow-attachment surface receding from the curtain and spacedacross the first flow path from said slit so that due to the Coandaeffect said high speed fluid curtain and any particles entrained by saidfluid curtain attach to the receding flow-attachment surface and arediverted along a second flow path defined by said flow-attachmentsurface.
 20. The method as set forth in claim 19 wherein the particlesare a mixture of particles capable of developing different inertias andwhich includes penetrating the fluid curtain with particles capable ofdeveloping sufficient inertia to penetrate said fluid curtain andremoving such penetrating particles, and entraining for movement withthe fluid curtain particles which do not develop sufficient inertia topenetrate the fluid curtain.
 21. The method as set forth in claim 20which further includes separating particles which penetrate the fluidcurtain into a first fraction which move along a path substantiallycoextensive with the first flow path, and a second fraction whichpartially turn with the fluid curtain and are then expelled therefrom.